IO-390-D Series Engine Maintenance Manual
72-30
© 2020 Avco Corporation. All Rights Reserved
Page 208
March 2020
IO-390-D Series Engine Maintenance Manual
8.
Piston Removal
NOTICE:
During removal of each piston pin (Figure 18), the piston will disconnect from the
connecting rod.
A.
Support the piston and remove the two piston pin plugs (Figure 18) and piston pin from the
piston.
Figure 18
Piston Assembly
CAUTION
ANYTIME A CYLINDER IS REMOVED, INSTALL TORQUE HOLD-
DOWN PLATES OR EQUIVALENT TO ENSURE A UNIFORM LOAD
ON THE MAIN BEARINGS IN THE CRANKCASE.
NOTICE:
During piston removal, support the connecting rod to prevent damage to the
connecting rods and crankcase:
B.
Remove the piston from the connecting rod.
C.
Install Torque Hold-Down Plates (ST-222) or equivalent as shown in Figure 19.
Figure 19
Torque Hold-Down Plates (ST-222)
CAUTION
DURING REMOVAL OF THE THREE PISTON RINGS IN THE NEXT
STEP, USE CARE NOT TO SCRATCH THE PISTON.
D.
Start from the top down, use the a commercially available piston ring expander tool to remove
the two top compression rings and the oil regulating piston expander ring (Figure 18).
